Toilet Closet Seal?

[DadRich]

I have a 2010 Jayco 28BHS. This year I am noticing odors in the bathroom that seem to be coming from the black tank. The flush valve seal appears good and holds water above it. I don't believe the odors are coming from the roof vent as the ceiling vent was closed a few of the times I have smelled the odor.
Does the closet rubber gasket go bad? The odor is not consistent, I just get a whiff of it every so often. (prior to using toilet).
Before I remove the toilet to inspect, I was looking for advice.
1. Does one simply just replace it every time you remove the toilet like the wax seals at home?
2. When I order a replacement rubber seal, are they more or less universal or brand/ model specific? Is there one that is better quality?
3. Assuming its similar to a home toilet removal, (remove water connection, unscrew the closet bolts, remove toilet) is there anything I should pay attention to while I have it removed? I.e. replace flush valve while you are at it, or don't touch the flush valve if its working fine. Should I improve anything while its off such as silicone/spray foam around the hole in the subfloor?
4. I have not seen any water at the base of the toilet. Would I be better off not disturbing the original seal and adding a venturi type roof vent (https://www.campingworld.com/cyclone-sewer-vent)

Thanks
Rich

[aws1957]

I have a jayfeather 2010 with the same problem

[Grumpy]

They are universal. Make sure the toilet flange and/or connecting pipe are not cracked. We had the small nipple connecting the flange to the tank crack on our 01 DESIGNER MH that created a similar issue.

[aws1957]

Thanks i will check that

[2edgesword]

The one time this happened to me was when the roof vent got blocked. Gas pressure builds up in the black tank and when you flushed that pressure was relieved through the toilet. I cleared the obstruction in the roof vent and smell went away.